Coronavirus pandemic update from the USA

This 1 April 2020 video from the USA says about itself:

Amazon Fires Employee Scared For His Life

Amazon fires an employee scared for his life amidst COVID-19. John Iadarola and Jayar Jackson break it down on The Damage Report.

Detroit Amazon workers strike to demand COVID-19 protection. By Jerry White, 1 April 2020. Amazon workers at the Detroit area DTW1 facility walked out Wednesday to demand the closure and sanitizing of the warehouse after a third worker tested positive for COVID-19.

Striking Detroit Amazon worker on Wednesday afternoon (Source: Facebook)

US Conference of Mayors survey shows severe lack of equipment to combat coronavirus pandemic. By Bryan Dyne, 2 April 2020. As the US death toll nears 5,000, a report to the federal government from mayors of 213 cities showing a desperate shortage of lifesaving equipment has fallen on deaf ears.

From daily The Morning Star in Britain:

Thursday, April 2, 2020

US nurses hold second day of protests against lack of PPE in hospitals

NURSES held a second day of protests across seven US states today to highlight a lack of protective equipment in Hospital Corporation of America (HCA) hospitals – the wealthiest privately run chain in the country.

“When we are infected, we become a real danger of infecting everyone else around us, patients, hospital staff, and a risk to our own families,” Kim Smith, a registered nurse in Texas said.

The protests, which started on Wednesday, were organised by the National Nurses United (NNU) union, which represents more than 10,000 nurses at HCA hospitals – privateers with a revenue of $46.7 billion in 2018.

Amid growing anger over criminal response to COVID-19 crisis, Washington threatens war. 2 April 2020. Trump issued threats against Iran and Venezuela yesterday, both weaponizing the pandemic and desperately seeking to divert mounting social tensions in the US itself: here.

By Steve Sweeney:

Thursday, April 2, 2020

US blocks medical aid to Cuba in show of ‘wild west brutality’

CUBA has blasted the continuing US economic blockade warning of a “violation of human rights” after a shipment of vital medical aid from China was stopped from reaching the country on Tuesday.

Washington was accused of acting with “Wild West brutality”, using the Covid-19 outbreak as an opportunity to “strangle the Cuban Revolution.”

“Cuba denounces the fact that medical supplies from Alibaba Foundation to help combat Covid-19 have not arrived in the country due to the criminal US blockade against the island nation,” President Miguel Canel-Diaz blasted.

By Steve Sweeney:

Thursday, April 2, 2020

Venezuela accuses US of deflecting attention from humanitarian crisis by sending war ships to region

VENEZUELA has accused Washington of using the deployment of warships to the region as a smokescreen to deflect attention from the “tragic humanitarian crisis” unfolding in the United States due to the corornavirus outbreak.

Foreign Minister Jorge Rodriguez made the charge after US President Donald Trump announced the move …

The Trump administration increased pressure on Venezuela last week when it placed a $15 million (£11.9m) bounty on the head of democratically elected President Nicolas Maduro.

The commander of the aircraft carrier USS Theodore Roosevelt has sent a four-page letter to his superiors appealing for the Navy to move nearly his entire crew into quarantine on the US Pacific island territory of Guam, where the vessel has docked since coronavirus infections were detected on board: here.

“Lies, damned lies, and statistics”—popularized by Mark Twain. As the number of confirmed coronavirus cases in the United States surpasses 200,000 and the number of dead nears 5,000, increasingly sophisticated justifications are being made for the continued inadequacy of the federal government’s response to the pandemic. One of the most recent is a study from the Institute for Health Metrics and Evaluation (IHME), which paints the massive outbreak in the country as nearly over, with two weeks to go until the worst is past: here.

Ten New York City transit workers die of COVID-19. By Sam Dalton, 2 April 2020. More New York City transit workers are sick and dying as work continues without protective equipment.

Without work and regular paycheck, millions of Americans at risk of eviction as rent comes due. By Jacob Crosse, 2 April 2020. In New York City, the epicenter of the coronavirus epidemic, up to 40 percent of tenants are expected forgo rent payments this month.

US Bureau of Prisons implements 14-day national lockdown as coronavirus pandemic takes hold. By Sam Dalton, 2 April 2020. The death of another inmate at the Oakdale Federal Correctional Institution in Louisiana was confirmed Wednesday, taking the total of deaths among those incarcerated at the prison to three.

Tennessee governor’s delay in issuing stay-at-home order means thousands more will die, physicians warn. By Warren Duzak, 2 April 2020. “This is not a mandated shelter in place order, but it is a strong urging for Tennesseans to stay at home,” Gov. Lee said during his daily media briefing: here.

American whooping cranes in danger

This December 2013 video from the USA says about itself:

This week’s moment in nature takes us among the whooping cranes of the Aransas National Wildlife Refuge in Texas.

From ScienceDaily:

Whooping cranes form larger flocks as wetlands are lost — and it may put them at risk

April 2, 2020

Over the past few decades, the critically endangered whooping crane (Grus Americana) has experienced considerable recovery. However, in a report appearing April 2 in the journal Heliyon, researchers found that habitat loss and within-species attraction have led whooping cranes to gather in unusually large groups during migration. While larger groups are a positive sign of species recovery, the authors say that these large groups mean that a disease outbreak or extreme weather event could inadvertently impact a substantial portion of this still fragile population.

Whooping crane conservation is one of North America’s great success stories,” says Andrew Caven, Director of Conservation Research at Crane Trust, a non-profit organization dedicated to the protection of critical habitat for whooping cranes and other migratory birds. During the 1940s the whooping crane population fell to 16 birds, largely due to overhunting. However, after concerted conservation efforts, their numbers have increased 30-fold. “We had this species at the brink of extinction, and now there are over 500 birds. As conservation biologists, we’ve been extremely inspired by that.”

Even with this boom in whooping crane numbers, researchers are observing larger migratory flocks than they would expect from population growth alone. Historically, groups of migrating whooping cranes seldom exceeded a family unit. “Twenty years ago, a group of nine was notable; something you’d write in your natural history notes about. But now it’s becoming something quite regular. In the recent years we’ve seen bird groups over seventy multiple times.”

With a total population of only around 500 birds, groups of this size could potentially put the whole species at risk. “The largest group detected was about 150 birds near Marcelin, Saskatchewan, which represents over one-fourth of the population. In a group that size, extreme weather like hailstorms or an outbreak of avian cholera could be catastrophic for the species,” says Caven.

So Caven and his research team set out to understand why traveling groups of whooping cranes had grown so large. They collected sightings data from state, federal, and private conservation organizations as well as the public along the whooping cranes migratory path from their Texas wintering grounds to their breeding grounds in Alberta, Canada.

Results indicated that the larger flocks of whooping crane roosted most frequently in the Southern Great Plains, where wetland habitats are sparse, but a few, high-quality conserved wetlands still stand.

“Many wetland habitats in the Great Plains have disappeared due to sedimentation or have been drained for farming” says Caven. “The rate of wetland loss has actually been quite high, particularly in these basins south of the Platte River.” With limited access to quality habitat in the southward part of their migration, it appears whooping crane have adjusted by gathering in proportionally larger assemblages.

As a sort of snowball effect, the authors say these gatherings can also be promoted by conspecific attraction or attraction to like individuals. The presence of birds in a location can make it more desirable for other cranes. “Conspecific attraction helps birds indicate optimal forging resources in these patchy environments and provide vigilance in situations that could be risky. These benefits could be a major reason we are seeing the emergence of these new behaviors as the cranes recover from near extinction,” he says.

Based on these findings, Caven suggests the best way to disperse these groups is to provide more wetland habitat throughout their migration path. “Supporting conservation groups that are restoring habitats south of the Platte River, particularly wetlands, can have a serious impact. Increasing the scale of wetland restoration within the migration corridor could break up these aggregations and provide foraging space for a ton of birds, not just whooping crane.”

The Crane Trust research team also plans to evaluate how habitat quality affects the length of time whooping cranes stay at stopover locations before continuing on in their migration. This will help determine those sites that are most essential in providing necessary resources for the birds to complete their 3,000-mile journey.

Coronavirus pandemic news, worldwide

This 28 March 2020 video from the USA says about itself:

Chris Hedges is a cultural icon in the US, up there with Noam Chomsky. His life experience, clearly presented in this video, is amazing, as is his unwavering dedication to his ethical principles. Roger Hallum, co-founder of the Extinction Rebellion (XR) interviews Chris in this riveting video. Their discussion ranges over the current #Coronavirus #Pandemic, #ClimateChange, as well as the morphing of democracy into fascism under our very noses. Part 2 will be published very soon as well.

Hospital closures continue in Germany despite COVID-19 pandemic. By Sybille Fuchs, 2 April 2020. Although every hospital bed in Germany is needed because of the coronavirus pandemic, many hospitals are facing closure, especially in more rural areas.

The number of confirmed cases of COVID-19 on the African continent as of Wednesday was 6,261 with over 200 fatalities: here.

19,000 ambulance workers strike in Northern India to demand protective gear. By Pradeep Ramanayake, 2 April 2020. The strike by Indian ambulance workers is part of the militant class response by the working class against the capitalist governments that have endangered the lives of workers amid the COVID-19 pandemic.

Sri Lankan medical experts demand mass coronavirus testing. By Naveen Dewage, 2 April 2020. The dangerous conditions facing millions of Sri Lankan workers, farmers and the poor are the result of decades of government cuts to the health system and other vital services.

A University of Indonesia report has warned that 240,000 people may die in the pandemic this month without a substantial government intervention: here.

COVID-19 infections hit Australian health workers. By Oscar Grenfell, 2 April 2020. Medical professionals across the country have made ongoing complaints that they lack sufficient quantities of personal protective equipment (PPE), including masks.

New Zealand workers speak out on unsafe conditions, wage cuts. By Tom Peters, 2 April 2020. Workers spoke to the WSWS about the lack of personal protective equipment and other safety measures.

Cowbirds, yellow warblers and red-winged blackbirds, research

This 2019 video from North America is called Male brown-headed cowbirds calling & spreading wings.

From the University of Illinois at Urbana-Champaign, News Bureau in the USA:

When warblers warn of cowbirds, blackbirds get the message

March 31, 2020

This is the story of three bird species and how they interact. The brown-headed cowbird plays the role of outlaw: It lays its eggs in other birds’ nests and lets them raise its young — often at the expense of the host’s nestlings. To combat this threat, yellow warblers have developed a special “seet” call that means, “Look out! Cowbird!”

In a new study, researchers at the University of Illinois at Urbana-Champaign report that red-winged blackbirds respond to the seet call as if they know what it means.

“Does this mean red-winged blackbirds understand that the call is specific to cowbirds or are they just responding to a general alarm?” said graduate student Shelby Lawson, who led the study with Mark Hauber, a professor of evolution, ecology and behavior at the U. of I. The researchers sought to answer that question by playing back the calls of several bird species in warbler and blackbird territories to see how the birds reacted.

They report their findings in the journal Communications Biology.

“We know that eavesdropping on the calls of other species is common across the animal kingdom,” Lawson said. “Birds do it. Mammals do it. There are studies of different primates that do it — and even birds that listen in when they do.”

In the rainforests of Ivory Coast, for example, tropical birds known as hornbills have deciphered some of the calls of the Diana monkey. The hornbills ignore the monkeys’ alarm calls for ground predators, which are no threat to the birds, but heed the monkeys’ calls for hawks, which are predators of hornbills.

Chickadees have very general alarm calls that we now know signal the size of different predators,” Lawson said. “A lot of birds will listen to these calls and respond based on the danger posed to them. There’s also a study of nuthatches listening to chickadee calls.”

But all these studies look at alarm calls directed at predators that can kill adult animals, Lawson said.

“Yellow warblers are the only bird we know about that has developed a specific call for a brood parasite,” she said. “When they see a brown-headed cowbird, yellow warblers will make the seet call and then females that hear the call will go back to their nest and sit on it tightly to protect their eggs. They only do this with cowbirds. They don’t seet at predators or anything else.”

In an earlier study, Lawson and her colleagues were playing audio of seet calls to study warbler behavior when they noticed that red-winged blackbirds were also responding aggressively to the calls. This prompted the new study.

To learn what the red-winged blackbirds understood about the calls, the researchers played a variety of bird calls in red-wing and yellow warbler territories and watched how the birds responded. They found that the red-winged blackbirds responded identically to the seet calls, the sound of cowbird chatter and blue jay calls — all of which signal a threat to their nests.

“They responded very aggressively to these calls, more so than they did to the warbler ‘chip’ call, which is just a general antipredator call,” Lawson said. When red-wings heard the warblers seeting, they flew close to the loudspeaker and looked around for the threat, she said.

When red-winged blackbirds see any kind of predator in their territory, they swoop at it and dive-bomb it. Male red-wings have so many mates in so many nests that they must defend a wide territory from interlopers and threats, Lawson said. This is why red-winged blackbirds are known as the “knights of the prairie.”

In defending their own nests from predators, they end up helping out other bird species — in particular, yellow warblers. Previous research shows that yellow warblers that nest near red-winged blackbirds suffer less from cowbirds laying their eggs in their nests.

The warblers also appear to help the blackbirds by warning of nest predators, the researchers said.

“We found that the red-winged blackbirds that nest really close to the warblers respond more strongly to the seet calls than those that nest far away,” Lawson said.

The researchers have more work to do to determine whether the blackbirds understand that the seet call means “cowbird”, specifically, or if it is just interpreted as a general danger to the nest. In a future study, the researchers will play the seet call to re-wings at the end of the nesting season to see if the blackbirds respond as aggressively to the sound after their eggs have hatched. Yellow warblers stop making the seet call when their nestlings are secure and too old to be bothered by cowbirds.

“This is the first report of a bird eavesdropping on another species’ warning of a brood parasite,” Hauber said. “We don’t yet know if the red-winged blackbirds understand that the warning is specific to cowbirds, but it’s obvious they understand that the call represents a threat to the nest — and that benefits them.”

The National Geographic Society supports this research.

Coronavirus pandemic news from Britain

This 1 April 2020 British TV video says about itself:

[Conservative] Communities’ Secretary Robert Jenrick clashes with Piers Morgan over the government’s lack of testing for Covid-19. The UK’s current testing rate is around 10,000 a day – but Germany is managing up to 500,000 a week. Piers and Susanna quiz Jenrick over the UK’s testing numbers and the government’s stance on people continuing to go out to work.

By Lamiat Sabin in Britain, Wednesday, April 1, 2020:

‘No immediate prospect’ of widespread Covid-19 testing for healthcare workers, NHS chief says

THE government came under increasing pressure over Covid-19 testing today as Britain experienced its biggest day-on-day rise in deaths so far.

Some 2,352 patients have died in hospital after testing positive for the virus as of 5pm on Tuesday, the Department of Health said.

This figure is up by 563 from 1,789 the day before.

By Bethany Rielly in Britain, 2 April 2020:

More doctors report being ‘gagged’ on PPE shortages

MORE doctors have reported being gagged from speaking out against shortages of personal protective equipment (PPE), despite government promises to end the silencing of NHS whistleblowers.

A dossier of evidence collated by the Doctors’ Association UK (DAUK), a medic-led campaign group, revealed on Tuesday widespread warnings to NHS staff not to speak to journalists.

It included at least two cases where medics were sent home for raising concerns over the lack of PPE.

By Bethany Rielly in Britain, 1 April 2020:

GP apologises for asking sick patients to sign ‘do not resuscitate’ forms if they contract Covid-19

A GP surgery in south Wales has apologised after asking people with serious illnesses to sign “do not resuscitate forms” if their health deteriorates after contracting coronavirus.

The Llynfi Surgery, in Maesteg, sent a letter to a “small number” of patients on Friday recommending they sign a do not attempt cardiopulmonary resuscitation (DNACPR) form.

The form would ensure that emergency services would not be called and resuscitation not performed if the patient’s health were to deteriorate from Covid-19.

By Bethany Rielly in Britain, 2 April 2020:

Key workers risking their lives on poverty pay must be paid at least £15 an hour, union demands

KEY WORKERS risking their health for poverty wages must be paid at least £15 per hour, a union is demanding.

Over three million essential workers are at high risk of exposure to the virus, according to a study by economic think tank Autonomy.

Yet more than one million of them are going home with extremely low wages, receiving pay below the poverty line.

By Alan Jones in Britain:

Wednesday, April 1, 2020

FIRMS should be closed down if they fail to comply with rules aimed at keeping workers safe, unions demanded today.

The TUC called on the government to take fresh steps to protect people still going into work, and said anyone who feared for their safety should not face punishment or dismissal.

Unions have voiced concerns that many employees who cannot work from home are being exposed to unnecessary Covid-19 risk because their employers are not putting adequate safety measures in place.

Nightingale field hospital completed in London to cope with mass coronavirus deaths. By Richard Tyler, 2 April 2020. While clearly the new hospital is a much-needed facility, given the criminal starving of resources in Britain’s health care system, for many who are taken there it will be little more than a waiting room for the dying.

Climate change threatens nightingale migration

This 2010 video from England is called Nightingale (Luscinia megarhynchos).

From the American Ornithological Society Publications Office:

Climate change may be making migration harder by shortening nightingales’ wings

April 1, 2020

The Common Nightingale, known for its beautiful song, breeds in Europe and parts of Asia and migrates to sub-Saharan Africa every winter. A new study published in The Auk: Ornithological Advances suggests that natural selection driven by climate change is causing these iconic birds to evolve shorter wings, which might make them less likely to survive their annual migration.

Complutense University of Madrid’s Carolina Remacha and Javier Pérez-Tris and their colleagues analyzed twenty years of data on wing shape variation and survival in two populations of nightingales from central Spain. They found that nightingales’ average wing length relative to their body size has decreased over the past two decades, becoming less optimal for migration. Shorter-winged birds were less likely to return to their breeding grounds after their first round-trip to Africa. But if this change in wing length is negatively affecting survival, what is driving it?

The “migratory gene package” hypothesis predicts that a suite of adaptations related to migration — including a long wingspan as well as a higher resting metabolic rate, larger clutch size, and shorter lifespan — may all be controlled by a set of genes that are linked so that selective pressures on one trait also affect the others. In recent decades, the timing of spring has shifted in central Spain and summer droughts have become longer and more intense, leaving nightingales with a shorter window in which to raise their young. This means the most successful birds may be those that lay smaller clutches of eggs, giving them fewer young to care for. And if natural selection is favoring smaller clutches, it may simultaneously push nightingales away from all of the linked traits in the “migratory gene package.”

Natural selection on clutch size that inadvertently leads to shorter wings and, therefore, reduced survival is an example of “maladaptation”, where organisms’ responses to changing conditions end up being harmful instead of helpful. “There is much evidence that climate change is having an effect on migratory birds, changing their arrival and laying dates and their physical features over the last few decades,” says lead author Carolina Remacha. “If we are to fully understand how bird populations adapt to new environments in order to help them tackle the challenges of a rapidly changing world, it is important to call attention to the potential problems of maladaptive change.”

Dutch museum buys ancient Viking ring

This 2 April 2020 video from Leiden in the Netherlands says about itself (translated):

The Netherlands Middle Ages collection of the National Museum of Antiquities is richer now because of this Viking ring. The ring was found in a cornfield near Hoogwoud, in the north of North Holland province. It is a silver ring from the tenth century. The Rijksmuseum van Oudheden recently bought the ring from the finder. In this video, curator Annemarieke Willemsen explains why the ring is so special.

See also here.

The museum is now closed because of the coronavirus crisis. The ring will be exhibited later.

Ancient human ancestors, new research

This 8 September 2019 video says about itself:

The film begins with the discovery of mysterious bones in the Rising Star cave system in South Africa, and introduces viewers to a previously unknown species of ancient human, Homo naledi.

From PLOS:

Homo naledi juvenile remains offers clues to how our ancestors grew up

This rare case of an immature fossil hominin sheds light on the evolution of human development

April 1, 2020

A partial skeleton of Homo naledi represents a rare case of an immature individual, shedding light on the evolution of growth and development in human ancestry, according to a study published April 1, 2020 in the open-access journal PLOS ONE by Debra Bolter of Modesto Junior College in California and the University of the Witwatersrand, Johannesburg, and colleagues.

Much research has gone into the evolution of ancient hominins — human relatives and ancestors — but little is known about their growth and development. Most hominin fossils represent adult individuals, and remains of developmentally young hominins are rare. This has left a gap in our understanding of how our ancient relatives grew from young into adults, and how modern human growth patterns evolved.

In this study, Bolter and colleagues examined fossils from the Dinaledi Chamber of the Rising Star Cave System in South Africa. This site is famous for providing abundant remains of the hominin Homo naledi, including individuals ranging from infants to adult. These fossils date to the late Middle Pleistocene, between 335,000 and 226,000 years ago, possibly overlapping in time with the earliest members of our own species. The team identified a collection of arm and leg bones and a partial jaw as the remains of a single young individual designated DH7.

The bones and teeth of DH7 were not fully developed and display a mixture of maturity patterns seen in modern humans and earlier hominins. DH7 is estimated to be similar in its developmental stage to immature specimens of other fossil hominins between 8-11 years old at death. The authors note, however, that if Homo naledi had a slower growth rate like modern humans, DH7 might have been as old as 15. Further study is needed to assess how Homo naledi grew and where it fits into the evolution of human growth and development.

Bolter adds: The rare juvenile Homo naledi partial skeleton will shed light on whether this extinct species is more human-like in its development, or more primitive. The findings help reconstruct the selective pressures that shaped extended maturity in our own species.

In recent years, scientists have uncovered evidence that modern humans and Neanderthals share a tangled past. In the course of human history, these two species of hominins interbred not just once, but at multiple times, the thinking goes. A new study supports this notion, finding that people in Eurasia today have genetic material linked to Neanderthals from the Altai mountains in modern-day Siberia. This is noteworthy because past research has shown that Neanderthals connected to a different, distant location — the Vindija Cave in modern-day Croatia — have also contributed DNA to modern-day Eurasian populations: here.

Albert Heijn corporation censors shop workers

This 31 March 2020 video from the USA says about itself:

CNBC’s Deirdre Bosa reports on strikes by workers at Amazon, Whole Foods and others as fears surrounding coronavirus grow.

Translated from Dutch NOS radio today:

Albert Heijn branch in Leiden under fire for photoshopping

An Albert Heijn branch in Leiden is under attack on social media after it posted an edited photo on Facebook. The photo shows that AH staff on the sidewalk are given a heart with the text ‘supermarket shelf fillers, we can not do without you’. But the original photo also had the text ‘minimum wage 14 euros’, which was removed in the version of the AH branch.

Albert Heijn has now removed the photo. “The photo was indeed edited”, said a spokesman. “The store is happy with all the statements of support. But removing part of the text was not convenient, the store now sees that.”

The chalk on the doorstep was an action by the FNV trade union, which wants a national minimum wage of 14 euros. Ruben Bres, one of the sidewalk warriors, told the local radio station Sleutelstad FM that these are hard times for the staff and that they are now extra appreciated.

This tweet says, translated:

So-called pride and gratitude for your workers, but photoshopping the text “minimum wage 14 euros” away? See picture.

Do you not even give your staff on the frontline of the fight against the corona crisis a decent income of 14 euros per hour?

How great cormorants hear, new research

This 2015 video from Britain says about itself:

BTO Bird ID – Cormorant and Shag

A black, reptilian-looking bird swims by low to the water – but is it a Cormorant or a Shag? Cormorants are more familiar and wide-spread, although Shags are more numerous. Let us help you to separate these two similar-looking species of waterbird.

From the University of Southern Denmark:

Surprising hearing talents in cormorants

April 1, 2020

Summary: The great cormorant has more sensitive hearing under water than in air. This new knowledge may help protect vulnerable bird species.

Many aquatic animals like frogs and turtles spend a big part of their lives under water and have adapted to this condition in various ways, one being that they have excellent hearing under water.

A new study shows that the same goes for a diving bird, the great cormorant.

This is surprising because the great cormorant spends most of its time out of the water. It is the first time we see such extensive hearing adaptations in an animal that does not spend most of its time under water, says biologist Jakob Christensen-Dalsgaard, University of Southern Denmark.

Human noise is a problem for animals at sea

Researchers are increasingly paying attention to the living conditions of animals living in or near the oceans.

Oceans are no longer the quiet habitats they used to be. Human activities produce noise — examples are ship traffic, fishing and windmill constructions, and this noise may pose a threat to the oceans’ animals.

“We need more knowledge about how animals are affected by this noise — does it impair their hearing or their hunting and fishing abilities? We have studied the effect on whales for some time now, but we don’t know very much about diving birds. There are many vulnerable animal species living or foraging at sea, that may be negatively affected by human noise,” says Jakob Christensen-Dalsgaard.

Listening for fish?

“Even though the great cormorant is not an aquatic animal, it does frequently visit the water columns, so it makes sense that it, too, has adapted its ears for hearing under water,” Jakob Christensen-Dalsgaard says about the new study.

Whereas the great cormorant spends about 30 seconds foraging under water in active pursuit of prey, approximately 150 other species of diving birds spend up to several minutes in pursuit of fish and squid.

Foraging under water is challenging for the sensory apparatus of the birds, however, and for most birds, their visual acuity under water is no better than that of humans. So, the birds may use other sensory modalities.

We know very little about birds’ hearing under water

Apart from a few behavioral studies, the hearing of birds under water is unknown.

Previously, researchers from University of Southern Denmark, have documented that great cormorants and gentoo penguins respond to sound under water, but this is the first study of the physiology of underwater hearing in any bird.

The study shows that the cormorant ear has been specialized for underwater hearing.

How was the study done?

To study hearing of the cormorant in air and under water the scientists measured auditory evoked responses and neural activity in response to airborne and underwater sound in anesthetized birds.

The neural responses to airborne and underwater sounds were measured using electrodes under the skin. In this way, the scientists could measure hearing thresholds to sound in air and under water.

Thresholds in water and air proved to be similar, with almost the same sensitivity to sound pressure in the two media. This is surprising, because similar sound pressures in air and water means that the threshold sound intensity (the energy radiated by the sound wave) is much lower in water, so the ear is more sensitive to underwater than to airborne sound.

The cost: Stiffer and heavier eardrums

“We found anatomical changes in the ear structures compared to terrestrial birds. These changes may explain the good sensitivity to underwater sound. The adaptations also may provide better protection of the eardrums from the water pressure,” says Jakob Christensen-Dalsgaard.

But there is — as always in Nature — a cost to these benefits:

Their hearing in air is not as sensitive as in many other birds. Their eardrums are stiffer and heavier.

How has the ear adapted?

The cormorant eardrum shows large vibrations in response to underwater sound, so the sensitivity likely is mediated by the eardrum and middle ear.

Underwater eardrum vibrations and anatomical features of the cormorant ear are similar to features found in turtles and aquatic frogs, that also appear to be specialized for underwater hearing.

The data suggest convergent modifications of the tympanic ear in these three distantly related species, and similar modifications may be found in other diving birds.